Probe localization

ABSTRACT

A method of NM image reconstruction, including:
         (a) acquiring a first set of NM data of a part of the body;   (b) collecting a probe position and/or probe NM data from an intrabody probe;   (c) reconstructing an NM image from said NM data using said collected probe data.       

     Also described is a method of navigating to a target in a body, including:
         (a) acquiring a NM image of a part of the body;   (b) collecting NM data from an intrabody probe;   (c) correlating said image and said data; and   (d) extracting location information of said probe relative to said target based on said correlated data.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/500,190, filed on Jan. 30, 2017, which is a National Phase of PCTPatent Application No. PCT/IB2015/055767, having International filingdate of Jul. 30, 2015, which claims the benefit of priority under 35 USC§ 119(e) of U.S. Provisional Patent Application Nos. 62/030,750 and62/030,825, both filed on Jul. 30, 2014.

PCT Patent Application No. PCT/IB2015/055767 is also related to:

PCT Patent Application No. PCT/IL2014/050086 filed Jan. 24, 2014,

PCT Patent Application No. PCT/IL2014/050088 filed Jan. 24, 2014,

PCT Patent Application No. PCT/IL2014/050089 filed Jan. 24, 2014,

PCT Patent Application No. PCT/IL2014/050090 filed Jan. 24, 2014,

PCT Patent Application No. PCT/IL2014/050246 filed Mar. 11, 2014; and

PCT applications and publications IB2015/053984 (filed on May 27, 2015);WO2015/104672; WO2015/033319 and WO2015/033317.

The contents of the above applications are all incorporated by referenceas if fully set forth herein in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates tonavigating a probe, such as a catheter or other intrabody probe and,more particularly, but not exclusively, to determining the positionand/or correct location of a probe using nuclear radiation emissions.

In some publications it is suggested to use a model of the anatomy,acquired, for example, by CT to constrain reconstruction of NM (nuclearmedicine) data.

SUMMARY OF THE INVENTION

There is provided in accordance with an exemplary embodiment of theinvention a method of NM image reconstruction, compromising:

(a) acquiring a first set of NM data of a part of the body;

(b) collecting a probe position and/or probe NM data from an intrabodyprobe;

(c) reconstructing an NM image from said NM data using said collectedprobe data.

Optionally, said collecting comprises collecting when contacting aboundary of a lumen by said probe. Optionally, said reconstructingcomprises using said boundary location as a constraint duringreconstruction. Optionally, said using as a constraint comprisesassuming emissions cannot come from said lumen. Optionally oralternatively, said reconstructing comprises reprojecting said NM datausing said constraint.

In some exemplary embodiments of the invention, the method comprisesreconstructing in a locality of said position.

In some exemplary embodiments of the invention, the method comprisesreconstructing at least a portion of a boundary of said lumen using aplurality of positions to cover at least 16 square centimeters andreconstructing comprises reconstructing an image of tissue adjacent saidportion.

In some exemplary embodiments of the invention, the method comprisesreconstructing at least a portion of a boundary of said lumen using aplurality of positions to cover at least 16 square centimeters anddisplaying a shape of said reconstruction with associated NM datacorresponding thereto.

In some exemplary embodiments of the invention, said reconstructingcomprises extending a model using said position of boundary.

In some exemplary embodiments of the invention, said reconstructingcomprises reconstructing without a structural image.

In some exemplary embodiments of the invention, said reconstructingcomprises reconstructing using a non-personalized anatomical model.Optionally, the method comprises matching said position to said model.Optionally, the method comprises estimating thickness of a wall at saidboundary using said matching and wherein reconstructing uses saidthickness. Optionally or alternatively, the method comprises defining aconstraint for reconstructing a hot spot using said matching.

In some exemplary embodiments of the invention, the method comprisescollecting both position and probe NM data. Optionally, saidreconstructing comprises using said probe NM data for reconstructing.Optionally or alternatively, said reconstructing comprises using saidprobe NM data for identifying a hot spot. Optionally or alternatively,the method comprises reconstructing a local NM image from said positiondata and said NM probe data.

In some exemplary embodiments of the invention, the method comprisesco-registering said probe position to said NM image. Optionally, saidco-registering comprises acquiring an x-ray image of said part and of atleast one marker whose position with respect to said NM data is knownand registering said x-ray image to said NM data and to said probeposition.

In some exemplary embodiments of the invention, no position data iscollected using a position sensor. Optionally, the method comprisesusing said probe NM data and said NM data to estimate a position of theprobe. Optionally or alternatively, the method comprises using saidprobe NM data to reconstruct an image.

In some exemplary embodiments of the invention, said probe is acatheter, said lumen is the heart and one or both of said NM data andsaid probe NM data comprises emissions from mIBG.

There is provided in accordance with an exemplary embodiment of theinvention apparatus comprising circuitry with one or more inputs forreceiving NM data, receiving probe position and/or NM data andreconstructing an NM image, for example, using methods as describedherein. Optionally, this is provided as part of a system comprising acatheter with one or both of a radiation sensor and a position sensor.

There is provided in accordance with an exemplary embodiment of theinvention a method of navigating to a target in a body, comprising:

(a) acquiring a NM image of a part of the body;

(b) collecting NM data from an intrabody probe;

(c) correlating said image and said data; and

(d) extracting location information of said probe relative to saidtarget based on said correlated data.

Optionally, said correlating comprises correlating said collected datawith an expected set of measurements calculated using said NM image.Optionally or alternatively, said extracting location informationcomprises verifying a position of said probe. Optionally oralternatively, said extracting location information comprises selectingbetween alternative posited positions of said probe. Optionally oralternatively, said extracting location information comprisesdetermining a position of said probe. Optionally or alternatively, saidextracting location information comprises determining a plurality offewer than 5 alternative positions of said probe. Optionally oralternatively, said extracting location information comprisesdetermining a proximity to a hot spot. Optionally or alternatively, themethod comprises combining said extracted information with position dataprovided by a position sensing system.

Optionally, said combining comprises providing a functional correctionusing said NM data to a physical position indicated by said positioningdata.

In some exemplary embodiments of the invention, said collectingcomprises collecting data with a substantially omni-directional sensor,with a directional sensitivity that is within a factor of 1:2 over alldirections. Optionally, collecting comprises moving said probe tocollect a non-scalar indication of NM data.

In some exemplary embodiments of the invention, said collectingcomprises collecting data with an asymmetric sensor, with a directionalsensitivity that is within a factor more than 1:2 for at least 1% of afield of view thereof. Optionally or alternatively, collecting comprisesmoving and/or rotating said probe to collect additional NM data for usein said correlating.

In some exemplary embodiments of the invention, said correlatingcomprises correlating based on a pattern of peaks and/or amplitude ofpeaks in said NM data.

There is provided in accordance with an exemplary embodiment of theinvention apparatus comprising circuitry with one or more inputs forreceiving NM image data, receiving probe NM data, correlating the NMdata and NM image data and extracting location information of saidprobe, for example as described herein.

Optionally, this is provided as part of a system comprising a catheterwith a radiation sensor.

There is provided in accordance with an exemplary embodiment of theinvention a method of NM image reconstruction, compromising:

(a) acquiring a first set of NM data of a part of the body;

(b) acquiring a second set of intrabody probe positions;

(c) reconstructing an NM image from said NM data using said collectedprobe data.

There is provided in accordance with an exemplary embodiment of theinvention a method of functional image reconstruction, compromising:

(a) providing a first set of anatomical data of a part of the body;

(b) acquiring a second set of intrabody probe positions and functionaldata using the probes;

(c) reconstructing an image from said functional data using saidcollected probe data and said anatomical data.

Optionally, said functional data comprises NM data.

There is provided in accordance with an exemplary embodiment of theinvention a method of functional hybrid imaging, compromising:

(a) acquiring a first set of functional data of a part of the body;

(b) acquiring a second set of intrabody functional data;

(c) reconstructing the hybrid image from said data.

Optionally, said functional data comprises NM data.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the invention pertains. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of embodiments of the invention, exemplarymethods and/or materials are described below. In case of conflict, thepatent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and are notintended to be necessarily limiting.

As will be appreciated by one skilled in the art, aspects of the presentinvention may be embodied as a system, method or computer programproduct. Accordingly, aspects of the present invention may take the formof an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system”.

Furthermore, aspects of the present invention may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.Implementation of the method and/or system of embodiments of theinvention can involve performing or completing selected tasks manually,automatically, or a combination thereof. Moreover, according to actualinstrumentation and equipment of embodiments of the method and/or systemof the invention, several selected tasks could be implemented byhardware, by software or by firmware or by a combination thereof usingan operating system.

For example, hardware for performing selected tasks according toembodiments of the invention could be implemented as a chip or acircuit. As software, selected tasks according to embodiments of theinvention could be implemented as a plurality of software instructionsbeing executed by a computer using any suitable operating system. In anexemplary embodiment of the invention, one or more tasks according toexemplary embodiments of method and/or system as described herein areperformed by a data processor, such as a computing platform forexecuting a plurality of instructions. Optionally, the data processorincludes a volatile memory for storing instructions and/or data and/or anon-volatile storage, for example, a magnetic hard-disk and/or removablemedia, for storing instructions and/or data.

Optionally, a network connection is provided as well. A display and/or auser input device such as a keyboard or mouse are optionally provided aswell.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent invention may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

Some aspects of the present invention are described below with referenceto flowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings. With specificreference now to the drawings in detail, it is stressed that theparticulars shown are by way of example and for purposes of illustrativediscussion of embodiments of the invention. In this regard, thedescription taken with the drawings makes apparent to those skilled inthe art how embodiments of the invention may be practiced.

In the drawings:

FIG. 1 is a schematic block diagram of a catheter-type probe and imagingsystem in accordance with some exemplary embodiments of the invention;

FIG. 2 is a schematic showing of a catheter for use in the system ofFIG. 1, in accordance with some exemplary embodiments of the invention;

FIG. 3A is a flowchart of a method of registration using the system ofFIG. 1, in accordance with some exemplary embodiments of the invention;

FIG. 3B is a flowchart of a method of image reconstruction using thesystem of FIG. 1, in accordance with some exemplary embodiments of theinvention;

FIG. 4 is a schematic showing of navigating to a target in accordancewith some exemplary embodiments of the invention;

FIG. 5 is a flowchart of a method of navigating using catheter basedsensing, in accordance with some exemplary embodiments of the invention;and

FIG. 6 is a schematic showing of signals detected by a probe followingthe showing of FIG. 4, in accordance with some exemplary embodiments ofthe invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates tonavigating a probe and, more particularly, but not exclusively, todetermining the location and/or correct location of a probe usingnuclear radiation emissions.

Overview

A broad aspect of some embodiments of the invention relates to using aprobe position for assisting NM image reconstruction and/or forreconstruction (e.g., into an image or map) of other functional datawhich has a low anatomical accuracy (e.g., lower than CT, for example,lower than 10 or 5 mm voxels). In some exemplary embodiments of theinvention, probe position is used to define anatomical locations whichcan be used to restrict reconstruction of the image so as to provide apossibly more accurate (e.g., anatomically correct) reconstruction.

In some exemplary embodiments of the invention, a plurality of probepositions are used to generate a representation of a structure of a bodypart. Optionally, previously and/or co-collected NM data set isregistered to the representation and the representation is used toassist in reconstruction of the NM data into an image and/or intodiscrete data suitable for overlap on a map or other model. In oneexample, the representation indicates a location of walls of a bodyorgan and the reconstruction constrains the NM data to reflect emissionsfrom the wall, rather than from voids. Optionally or alternatively, thereconstruction is used to select data from the NM data to be used foranalysis. Optionally or alternatively, the reconstruction is used toidentify, in the NM data, location(s) of interest and/or indicate adesired identification of an object for the NM reconstruction, forexample, the identification of a ganglion.

In some exemplary embodiments of the invention, the reconstruction doesnot use a previously acquired structural 3D image, such as a CT image.Optionally or alternatively, the reconstruction does not use ananatomical model.

In some exemplary embodiments of the invention, the probe positions areused to extend a previously acquired 3D image (e.g., structural and/orfunctional) and/or a model. In one example, the extension is bymodifying the model and/or model parameters according to actual and/orcurrent tissue shape. For example, the image and/or model is deformedand/or constrained to match measured probe locations. Optionally oralternatively, extension is in time, for example, starting from a modelat one part of a cycle of deformation of an organ, probe positionsmeasure the position of organ parts over time and show how the model isto be deformed from one state to its shape in other parts of the cycle.

Optionally or alternatively, extension is in space, for example, if themodel shows only part of the organ, the positions can be used to extendthe model to unmodeled portions and/or to provide more resolution withinthe model (e.g., between points of the model).

A broad aspect of some embodiments of the invention relates to using NMemissions to locate a catheter or other intrabody probe with respect toa navigation target.

In some exemplary embodiments of the invention, the locating comprisesdetermining if the catheter is at an expected location.

In some exemplary embodiments of the invention, the locating comprisesdetermining if the catheter is at and/or correctly oriented with respectto a navigation target.

In some exemplary embodiments of the invention, the locating comprisesdetermining a general position of the catheter with respect to anavigation target.

In some exemplary embodiments of the invention, the locating comprisescollecting information to assist in reconstructing an image of thetarget location.

In some exemplary embodiments of the invention, navigating is providedwhich uses both NM location information and other information, such as apreviously or co-acquired image (e.g., structural and/or functional).

In some exemplary embodiments of the invention, locating uses a map ofradiation emission previously or co acquired. Optionally, such a map isused to estimate what signals should be captured by an intrabody probeand/or the likelihood that captured signals reflect the target location.

In some exemplary embodiments of the invention, locating compriseslocating using a position sensor on the probe which is optionallyco-registered with other data.

In some exemplary embodiments of the invention, such a position sensoron the catheter is used to co-register the catheter with a co-acquirednuclear medicine image of, for example, the heart. Optionally, thepatient has affixed thereto a position sensor or other marker (e.g.,visible in x-ray) which is also visible in a NM imager (e.g., includingradioactive material). The catheter is then used to contact variousparts of an organ, e.g., the heart and collected information therefrom.In exemplary embodiments of the invention, such contacting can be usedto determine a heart wall (or other lumen wall, e.g., for other organs)location. Optionally or alternatively, such contacting is used toextract from the NM image and/or NM data the expected emission to bemeasured by the catheter (if the catheter has a radiation sensor).Optionally or alternatively, actually measured emissions and/ordetermined wall locations are used to guide a reconstruction process ofthe NM image. In one example, the NM image is used to search forganglions or other ANS (Autonomic nerve system) components or otherparts of an image which are localized and have a relatively high (orlow) activity.

For example, wall location can indicate where such a part may bephysically located and thus, to be searched for, e.g., using a window onan image or data. In another example, emission measurements can be usedas a seed for indicating a possible location for a ganglion.

In some exemplary embodiments of the invention, the knowledge of theprobe used for sampling data and its related sensing area (e.g., afunctional, ƒ which indicates a spatial behavior of sensing) aresuperimposed (location wise) on a co-located image, such as ananatomical image. In some exemplary embodiments of the invention, themultiple functionals, ƒ, acquired at different locations and/ororientations are input into a maximal likelihood reconstructionalgorithm that has the anatomical knowledge as a prior constraint anduses the set of functionals and their sampling locations to generate areconstructed NM image of the organ.

An aspect of some embodiments of the invention relates to interplaybetween location information and the physical information sensed at alocation. In some exemplary embodiments of the invention, theinformation regarding location is improved using information gatheredfrom the physical properties at a location and/or vice versa.Optionally, multiple iterations are provided of one informationimproving different information.

In some exemplary embodiments of the invention, even if the positionsensor is precise, if tissue moves and/or deforms, the position relativeto the tissue and/or anatomical objects may be less precise, while whatmay be more important is the position relative to functional parts.Optionally, a functional position is used to correct/update/replace thesignal.

In one example, the knowledge that a blood vessel has a wall and thefact that from physical information one can detect the location of thewall, allows one to relate to this information and use it to gain moreinformation on the location of the probe (e.g., select betweenalternative probe position reconstructions), which may be useful, forexample, in impedance based position sensing.

In another example, detecting that a catheter contacts a wall allowsmeasured functional information (e.g., conductivity or radiation) to bereconstructed more accurately.

In some exemplary embodiments of the invention, the gain of informationfrom the location or the physical property at a location can be furtheraugmented if there is a co-registered set of anatomical information(such as a CT or an MRI). However, in some embodiments of the invention,what is used are rules, for example, that blood vessels are cylindricaland/or general anatomical models, such as the general layout anddiameter of blood vessels and/or other hollow organs. Optionally oralternatively, conductivity is used to distinguish walls from blood,based on a threshold value or other method which distinguishes betweenvalues representative of wall tissue and values representative of blood.

In some embodiments, the bifurcations of blood vessels (e.g., asdetected using a position sensor) is used to identify a location wherethe anatomical constraints (e.g., used to constrain a positionreconstruction of the probe) change (e.g., more than one cylindricallumen to be in).

An aspect of some embodiments of embodiments of the invention relates toreconstructing a functional image (e.g., NM) using both data acquiredfrom outside the body and data acquired from inside the body. Inexemplary embodiments of the invention, the data acquired inside thebody is acquired using a probe and is used to enhance data acquired fromoutside the body. Optionally, position sensing of the probe is used tocorrelate the two types of data and/or to help reconstruct one or bothtypes of data.

In some exemplary embodiments of the invention, the data acquired fromoutside the body and the data acquired from inside the body are ofdifferent modalities.

Optionally or alternatively, the data is of a same modality but of adifferent type, for example, NM data using different tracers and/oracquired at different physiological states.

An aspect of some embodiments of the invention relates to functionalimage reconstruction from functional data using a plurality of probepositions. Optionally, the functional data is acquired by the probes.Optionally or alternatively, the functional data is acquired using adifferent imager on the same patient. For example, an external NM imagermay be used, for example an imager with detectors which can be broughtclose to the tissue being imaged.

In some exemplary embodiments of the invention, the probe positions areused to define one or more anatomical restrictions on reconstruction.Optionally, these restrictions are also defined using separatelyprovided anatomical data (e.g., images, models, rules, from same and/orother patients). Optionally, the provided anatomical data is used as amodel to be corrected by said probe position data. Optionally oralternatively, the anatomical data is used to improve positioning dataof the probes.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not necessarily limited in itsapplication to the details of construction and the arrangement of thecomponents and/or methods set forth in the following description and/orillustrated in the drawings and/or the Examples. The invention iscapable of other embodiments or of being practiced or carried out invarious ways.

Exemplary System

FIG. 1 is a schematic block diagram of a catheter and imaging system 100in accordance with an exemplary embodiment of the invention.

A patient 102 includes a heart (or other organ) 104 with a target 106characterized by a radioactive emission when patient 102 is injectedwith a suitable radioactive marker.

An optional x-ray imager 108 (e.g., a fluoroscope) acquires an image ofpatient 108 with a field of view 110 and optionally one or moreradio-opaque markers 112. As noted below, markers 112 may also beradioactive.

In an exemplary embodiment of the invention, system 100 is used with acatheter 114. A position sensing system 116 may be used to determine theposition of catheter 114 (e.g., a tip thereof) and/or of other parts ofsystem 100, such as markers 112 (e.g., by touching a position sensorthere to, or if they include a position sensor).

NM (Nuclear medicine) data 118 may be provided, for example, fromstorage and/or using a NM imager (not shown). Optionally, the NM imageris used while catheter 114 is inside patient 102.

A processor 120 optionally analyses an acquired image from x-ray imager108 for detecting markers 112 therein and optionally is used (e.g., asdescribed below) to register the NM data to the catheter location and/orx-ray image. Optionally or alternatively, for example, as describedbelow, processor 120 reconstructs a NM image from NM data 118, usingpositions indicated by position sensing system 116. In some exemplaryembodiments of the invention, only processor 120 is provided and theother components are standard components.

A display 122 optionally shows one or more of a reconstructed NM image,catheter position (e.g., in space) location (e.g., relative toanatomical locations) and/or the image from imager 108.

Exemplary Catheter

FIG. 2 is a schematic showing of a catheter 200 for use in the system ofFIG. 1, in accordance with some exemplary embodiments of the invention.Optionally, catheter 200 is designed for traveling in blood vessels, forexample, including a hydrophobic coating and/or has a suitable diameter(e.g., less than 5 mm, 3 mm, 2 mm or intermediate or greater sizes)and/or a suitable length (e.g., between 10 cm and 300 cm, for example,between 50 and 250 cm). Optionally or alternatively, catheter 202 is inthe form of an endoscope (e.g., and may include an imager thereon), forexample, for traveling through natural and/or unnatural voids in thebody. Other intrabody probes (e.g., flexible, bendable and/or rigid),may be used instead of a catheter, for example, a colonoscope or otherimaging probe.

As shown, catheter 200 has a body 202 and one or more components,optionally at or near its distal tip. In an exemplary embodiment of theinvention, an optional position sensor 204 (e.g., a magnetic fieldsensor as used in the Biosense-Webster CARTO® system), is provided.Optionally or alternatively, one or more electrodes 212 is provided, forsensing and/or for stimulating tissue. Optionally or alternatively,other tools, for example, one or more of a biopsy snare, injectioncatheter, cryo-catheter or probe, and microwave probe or catheter, areprovided.

Optionally or alternatively, a radiation sensor 206 is provided.Optionally, radiation sensor 206 is an omni-directional sensor.Optionally or alternatively, sensor 206 includes shielding 208 at one ormore sides thereof, and/or is otherwise configured have a non-sphericalsensitivity. Optionally or alternatively, shielding 206 includesapertures 210 (optionally shielding 208 being in the form ofcollimators), to provide (relatively) narrow field sensitivity.Optionally, the detector has a factor of sensitivity of greater than1:1.5, 1:2, 1:4, 1:6, 1:10 or intermediate factors between differentdirections of viewing, for at least 10% (vs. a different 10%) of asurface area of the detector.

Optionally, the various sensors and/or electrodes communication using awire or bundle that runs along catheter body 202.

In some embodiments position is detected using non-sensing methods, forexample, by extracting catheter position for one or more x-ray images orby analyzing signals injected by the electrode and detected using one ormore surface electrode.

Exemplary Registration

FIG. 3A is a flowchart 300 of a method of registration using the systemof FIG. 1, in accordance with some exemplary embodiments of theinvention.

At 302, one or more markers are optionally attached to patient 102.Optionally, the markers are both radio-opaque and radioactive.Optionally, the markers include a position sensor therein. Optionally,markers as described in co-filed application of same date and inventorBen-Haim with PCT Patent Application No. PCT/IB2015/055772 filed Jul.30, 2015, now published as WO2016/016839, and which entered NationalPhase as U.S. patent application Ser. No. 15/500,189, filed Jan. 30,2017, published as 2017-0278280-A1, are used, which include both aradio-opaque section and a radioactive section (optionally removable).

At 304, an NM image of the patient is acquired. Optionally, the NM imageis registered to body coordinates using the markers. Optionally oralternatively, other registration methods are used, for example, using atransmission CT image. However, a particular feature of some embodimentsof the invention is that no CT image is acquired, thus potentiallyreducing the patient radiation load.

At 306, a catheter (e.g., catheter 200) is used to acquire locations ata plurality of reference points (e.g., in the heart, two or three ormore of LSPV, LIPV, RSPV, RIPV, LV Apex). In an exemplary embodiment ofthe invention, the locations are acquired by navigating the catheter toa location and then “capturing” and “naming” the position of thecatheter to processor 120.

At 308, the catheter and markers are optionally imaged using an x-rayimager. In some embodiments, no X-ray imaging is used and, for example,the markers need not be radio-opaque. Instead, the positions of themarkers are registered to the position sensor, for example by contactingof the catheter or a different position sensor thereto.

At 310, the positions of the markers is acquired, for example, bycontacting with a position sensor (e.g., optionally before 308 or 306).

At 312, the NM data can be registered to the x-ray image, markers and/orposition sensing space, using the above measurements. In an exemplaryembodiment of the invention, this registration is used to register theinstant catheter tip location to the NM data space.

In some exemplary embodiments of the invention, other registrationmethods are used to register the NM data space to the location of thecatheter tip. In one example, position sensing is replaced or enhancedby a method of tracking displacement whereby an integration of 3Ddisplacements from a known location are used to determine a currentlocation. Optionally, this displacement is periodically zeroed byreturning the catheter to a known location (e.g., a fixed part, such asa valve or apex), of the heart. Optionally, the displacements aredetermined using a 3D accelerometer and/or gyroscope at the cathetertip, for example, using calculations of a type used in INS (inertialnavigation systems).

Exemplary Image Reconstruction

FIG. 3B is a flowchart 320 of a method of image reconstruction using thesystem of FIG. 1, in accordance with an exemplary embodiment of theinvention, in which locations of the catheter tip are used to constrainNM image reconstruction, optionally by defining location where emissionis expected and/or locations where emission is unexpected.

At 322, the tip (or other known part) of catheter 200 is placed againsta wall or other structure from which and/or relative to which emissionsare expected or expected not to be. This can be used, for example, toassess the shape of a lumen surrounding catheter 202 and/or to guidedata acquisition and/or analysis, for example, as described below.

At 324, a radiation signal is optionally sensed (e.g., if sensor 206 isprovided). In an organ such as the heart, signal from tissue directlyadjacent the sensor and/or in its main field of view is expected to be asignificant if not a majority of a signal acquired by sensor 206. If thecatheter is against tissue that does not uptake the tracer, no signalfrom directly adjacent tissue is to be expected. Optionally, the sensedsignal is marked with respect to catheter tip position and/ororientation (e.g., using position sensor 204). In some embodiments, forexample, as described below, a position sensor is not provided, instead,the sensed radiation signal is used for position estimation with and/orwithout wall contact.

At 326, a plurality of tip positions are used to reconstruct the shapeof at least part of the lumen (e.g., a heart chamber or wall sectionthereof, for example, a left ventricle or a left or a right atrium).Optionally, electrical sensing is used to gate the position sensing to asame part of the cardiac cycle for all measurements. Optionally oralternatively, a plurality of positions are acquired at each wallcontact, allowing the location of the wall (and/or lumen shape) atdifferent parts of the cardiac cycle to be reconstructed, optionallywith measurements being binned according to cardiac cycle, extracted,for example, from ECG data and/or from change in position of thecatheter within a cardiac cycle. Such windowing, triggering and/orgating is optionally and/or alternatively used also for collectingradiation information. Optionally, catheter movement within 1 second isassumed to be due to tissue movement and not due to operator movement.Optionally or alternatively, an operator can indicate when he is notproviding movement, for example, using a foot control. Optionally oralternatively, a sensor in the port and/or catheter can indicaterelative movement of the catheter and port. Optionally or alternatively,a sensor in a manipulator (e.g., for bending catheters) is used todetect human, vs. tissue caused movement. Optionally or alternatively,an x-ray image is analyzed to determine a cause of movement, forexample, by measuring a catheter length inside the body and/or movementof a catheter tip relative to heart wall or other anatomical markers.

In an exemplary embodiment of the invention, the wall locations are usedto build a mesh model of the lumen wall. Optionally, this model iscorrelated with a known anatomy (e.g., general human anatomy and/or apreviously acquired image). Optionally, such correlation may be used todetermine structural feature snot at the lumen surface, for example,wall thickness, identification of the anatomical location and/orexpected nearby possibly emitting structures and/or non-emittingstructures, for example, the mitral valve annulus ring will havedifferent (if any) emitting properties and has a generally known shape.Optionally, wall thickness is used for reconstructing, for example asdescribed below. Optionally or alternatively, anatomical location isused to refer back to an anatomical model which may be used, forexample, for navigation and/or diagnosis (e.g., with the data projectedonto such a model, rather than using only the acquired mesh).Optionally, the anatomical model is modified (e.g., resized, rotatedand/or deformed) to match or approximate the acquired mesh model.Optionally, the deformation is local, for example, to areas of between 1and 5 cm in diameter.

In an exemplary embodiment of the invention, the mesh has an averagecell size (e.g., corresponding to spatial sampling rate) of less than 30mm, less than 20 mm, less than 10 mm or intermediate or greaterdiameters, for an area of, for example, at least 10 cm{circumflex over( )}2, 20 cm{circumflex over ( )}2, 40 cm{circumflex over ( )}2, 80cm{circumflex over ( )}2 or intermediate mesh sizes. Optionally, themesh cell size is selected according to a desired resolution and/or adesired motion-related accuracy. For example, mesh size may be smallerthan 5 times, 3 times, 2 times, or 1 time the wall thickness. In anexemplary embodiment of the invention, the cardiac cycle is divided intoat least 2, 3, 4, 5, 8 or smaller or intermediate numbers of differentstates. The number of states may be different for different parts of theheart, for example, fewer states where there is less data and/or lessmotion.

At 328, NM data correlated with the catheter tip position is optionallyextracted. Optionally, a predefined shape for extraction is provided.Optionally or alternatively, a shape based on the anatomy is extracted.Optionally, the activity in this extracted portion is compared to theactivity sensed by the catheter. This may be used, for example, fornavigation and/or to detect changes in activity. Optionally oralternatively, the activity is displayed (e.g., color coded) on display122, optionally overlaying the anatomical model. Optionally, localactivity is activity in a cube with a width of 3 mm, length of 3 mm andheight of 8 mm with respect to the tip (e.g., long axis perpendicular orat an angle to lumen wall).

At 330, a reconstruction zone is optionally defined. In some exemplaryembodiments of the invention, the reconstruction zone defines the wallsof the lumen, for example, based on the acquired positions and/or model.Optionally or alternatively, the reconstruction zone defines a locationrelative to the probe, for example, wall in contact with the probeand/or tissue on the other side of the wall.

At 332, the NM data is reconstructed using the defined reconstructedzone. In some exemplary embodiments of the invention, NM data isreconstructed and/or re-projected to be constrained to avoid the hollowof the lumen. In some exemplary embodiments of the invention,determination of the wall is used to define locations where highemitting objects (e.g., ganglions) may be located. Reconstructioncomprises searched for such objects and/or determining if areconstruction of a ganglion at such locations is reasonable. Exemplaryreconstruction techniques which may be used are described in PCTpublication WO2014/115148, the disclosure of which is incorporatedherein by reference.

Optionally, such searching is in a volume within (for example) 1 cmdistance from the lumen wall.

In some exemplary embodiments of the invention, reconstruction comprisesreconstructing a locality of the probe, for example, using extracted NMdata and/or sensed NM data. Optionally, such reconstruction uses thewall location to limit reconstruction from “leaking” into the lumen.

In some exemplary embodiments of the invention, the NM imaging comprisesimaging using a nerve imaging agent such as mIBG, and the searchingcomprises searching for ganglions as being objects of a generallyspherical or ellipsoid or almond like shape and a size of long axis ofbetween 5 and 22 mm. It is noted that mIBG may also be used to detectandrogenic synapses in muscle tissue, possibly indicating a level ofnervous control of such tissues.

In some exemplary embodiments of the invention, the NM imaging comprisesimaging using a muscle metabolic agent, such as Sestamibi and theimaging indicates the extent and/or viability of muscle, such as cardiacmuscle.

In some exemplary embodiments of the invention, the NM data and the NMprobe data relate to emissions of different radioactive tracers. Forexample, the NM data may be of Sestamibi and the probe data of mIBG.Optionally or alternatively, the NM data includes multiple tracer data.In some exemplary embodiments of the invention, the NM data is useful,for example, for navigation and/or reconstruction, as all the tracerscan share of different concentration in solid tissue as compared toblood (e.g., and can be used to indicate at least part of the shape ofthe heart, possibly enough for model matching with boundary locationsdetermined by the position sensor).

Optionally or alternatively, the relative positions of the two tracersmay be expected, for example, mIBG concentrations being within or nearviable muscle indicated by Sestamibi. Optionally or alternatively, theprobe is used to identify location having a mismatch between theradiation indicated in the NM data (e.g., Sestamibi) and instantradiation (e.g., mIBG). This may indicate various pathologies, forexample, as described in the above mentioned related applications, forexample, WO2015/033317, the disclosure of which is incorporated hereinby reference.

Exemplary Navigation

In an exemplary embodiment of the invention, NM data collected bycatheter 200 is used to assist in navigating to a target and/orotherwise determining the catheter location.

FIG. 4 is a schematic showing 400 of navigating to a target inaccordance with an exemplary embodiment of the invention. In the exampleof navigating to a hollow organ, such as a heart via the vascularsystem, a catheter 200 may travel along a lumen 402 (e.g., the aorta),to an organ 404 (e.g., the heart) to a target location 410 (e.g., alocation to be ablated in organ 404). A probe other than catheter 200may be used and for other organs. Also, the pathway may be via tissue oran artificial lumen, rather than natural lumens such as the vascularsystem or GI tract. In FIGS. 4, 412 and 408 indicate otherradio-emissive locations in the organ which are not the target and aradio-emissive location 406 (e.g., the liver) which is not in organ 404.References 414-424 indicate various locations at which navigationactivities are carried out in accordance with some embodiments of theinvention and as described below. FIG. 6, explained below, showsradiation measurements taken at such locations, in accordance with someembodiments of the invention.

FIG. 4 illustrates various ways of navigating, one or more of which maybe applied in some embodiments of the invention. FIG. 5 is a flowchart500 of a method of navigating using catheter based sensing, inaccordance with an exemplary embodiment of the invention.

At 502, the catheter location is optionally determined using a positionsensor (e.g., 204). It should be noted that there are severalpositioning coordinates to be considered in some embodiments of theinvention. One is the physical location, for example, absolute locationin space and/or relative to an anatomical location, usually denotedherein as “position”. Another is a functional location, relative to afunction in tissue (e.g., distance from a metabolic hotspot). Such aposition may also be binary, being either at the location or not.Functional location and anatomical location are usually denoted hereinas “location”.

At 504, a radiation signal is sensed from catheter 200. In someembodiments, the signal is scalar and indicates a strength of detectedemission. This may correlate with a distance from one or more hotspotsbut will generally not give direction.

Optionally, the catheter is moved, so as to provide multiple suchmeasurements, optionally using a position sensor and/or measurement ofchange in catheter insertion, to build a spatial or linear map ofdifferent measurements at different locations. Optionally oralternatively, the catheter is asymmetrically sensitive and isoptionally rotated so as to provide different measurements fromdifferent directions.

At 506, expected measurements are determined. For example, he expectedradiation measurements may be calculated from the position of thecatheter, the detector spatial sensitivity and a previously or coacquired NM data set. Optionally, the data set is corrected for aneffect of delay between imaging and catheter navigation, for example,using models of tracer redistribution and/or decay. Optionally oralternatively, catheter measurements (or measurements with a differentradiation sensor, for example, near the heart and/or the liver,optionally from outside the body) at one or more locations are used tonormalize the NM data model.

In some cases location data is used. For example, using a previously orco-acquired structural data, an expected position of the catheter (e.g.,“should be within aorta”) is provided. Optionally, the position data(e.g., a series of locations and/or orientations) is used to detectmotion along a straight and/or curved and optionally constricted pathway(e.g., a particular blood vessel as an example of a pathway with agenerally known geometry), for example, detecting the traversal of anaortic arch based on a 180 degree change in catheter path and a suitablebending radius.

At 508, the expected data is correlated with the measured positionand/or radiation data. The correlation may be used, for example, to finda correct match, to find a best match and/or reject matches.

At 510, in some exemplary embodiments of the invention, a correct matchis optionally used to determine a location of the catheter based onmatching of data to the expected data associated with a certain position(e.g., verification). Optionally or alternatively, a correct match isused by searching the space of possibilities for a position where themeasurements match the expected data. This may be used to find alocation. Various search mechanism may be used, including, for example,pattern matching and a priori-reduction of possible matches byprocessing the data to extract one or more features which are expectedin the measured data.

In some exemplary embodiments of the invention, a correct match is usedto verify if the catheter is at an expected location or not. Optionally,any match below a threshold is indicated as a failure.

In some exemplary embodiments of the invention, a best match is used toestimate a catheter position. Optionally, matching comprises using bothposition data and radiation data, for example, weighted and/orcross-verified (e.g., a match is considered only if both position andradiation data meet certain quality criteria).

Optionally or alternatively, a best match is used to decide between asmall number of alternative navigation options. For example, a bestmatch may be used to indicate if the catheter is in one heart chamber oranother, or if the target is generally to the right or to the left.

Referring back to FIG. 4 for examples or using position data and/orradiation data, at 414, radiation data may be unable to indicate morethan a very general position. Position data may indicate if the catheterleft vessel 402 to a branching vessel.

At 416, position data may indicate the curve in travel and radiationsensing may indicate a proximity to radiation sources and/or the generalspatial distribution of 406 on one side and 408-412 on the other side ofthe position.

At 418, as organ 404 is entered, position data may indicate ability tomove in various directions and radiation data may indicate radiationsources at relative proximity and at various directions.

At 420, radiation measurement signals are expected to increase,indicating that even a scalar measurement of radiation signal may beused to assist in navigation (e.g., detecting increase as target 410 isapproached).

At 422, near a hotspot 412 (not target 410), radiation intensity may becorrect, however, position and/or radiation signals from otherdirections may be incorrect.

At 424, all the indicators match up. Optionally, radiation intensity isused to verify maximum proximity to a hot spot and/or guide rotation ofcatheter 200 so that, for example, a desired portion thereof (if any,such as an ablation mechanism) is in contact with the wall of organ 404.

Optionally or alternatively, to position data, other data may be used toassist in navigation. For example, structural data such as from a CT,ultrasound, MRI or x-ray image may be used to provide anatomicalconstraints on possible locations for the catheter. Optionally oralternatively, functional data, such as electric or magneticmeasurements may indicate relative position on and/or distance from thewall of an electrically active organ. Optionally or alternatively, otherdata may be collected and/or displayed, for example, one or more ofpressure, displacement, heat and/or conductivity. In an exemplaryembodiment of the invention, such other data may be useful if there is amap indicating expected properties and/or values for such data at eachpoint and/or at points of interest.

Exemplary Correlation for Navigation

FIG. 6 is a schematic showing of signals which might detected by a probefollowing the showing of FIG. 4, in accordance with an exemplaryembodiment of the invention.

The traces shown in FIG. 6 are angular traces (2D for simplicity ofshowing, but may be 3D), with the x-axis being an angle (straight aheadbeing at the middle of the x-axis) and the y-axis indicating amplitudeof signal. Noise is generally not shown, but it is noted that the signalis generally noisy, which may lead to a need to collect data over aperiod of time. Optionally or alternatively, data is collected as thecatheter is moved and navigational conclusions updated during suchmovement and displayed. Optionally, a display shows both an anatomical(e.g., relative to torso markers 112 and/or internal anatomy) and/orfunctional position. In some embodiments, changes in functional positionare used to update the displayed anatomical data (e.g., indicating thatthe heart moved, based on movement of hot spots thereof).

Reference 602 shows a signal as might be measured at 414. A generallylow amplitude and angularly wide peak indicates the distance and spatialdistribution of radiation emission targets.

Reference 604 indicates a signal as may be measured at 416, the dualpeaks indicate that source 406 is to one side and sources 408-412 (notdistinguished) are to another side. Based on the previously acquiredmodel of the NM data, this suggests guiding the catheter to the left. Ifonly a scalar signal is measured, it is expected that the measuredamplitude increase towards location 416 and then decrease as thecatheter moves away (possible increasing again when entering the organ).

In some exemplary embodiments of the invention, an expected measuredsignal may be provided by analyzing the NM data (e.g., image) andsimulating a travel of the catheter in that data. Such an expectedsignal can be a 1D signal or a 2d or 3D or 4D signal (with one dimensionbeing time or location along the path). Optionally or alternatively,signals expected if the catheter is incorrectly navigated are alsogenerated. Optionally, the system can show to the user the expectedsignal and/or signal gradient. Optionally or alternatively, the systemcan generate an alert if the catheter deviates from such an expectedsignal, for example, using processor 120.

Reference 606 indicates a signal as may be measured when entering organ404 and which shows peaks corresponding to each of hot spots 408, 410and 412. In an exemplary embodiment of the invention, the relativeangular position of the peaks is used to determine catheter position. Itmay be expected that as catheter 200 advances to location 420, the peakswill move apart and increase in intensity.

In one example, signal 606 is correlated to the NM data by generating anarray of signals as expected to be measured from multiple locations inthe body (e.g., locations along the path and/or with organ 404).Correlation can then be used to find one or more best and/or acceptablefits. Optionally or alternatively, expected signals are generated(and/or refined and/or searched) on the fly based on an expected and/orestimated position(s) or range(s) of positions of the catheter. In someembodiments correlation is statistical, in that different possibilitiesare given a different probability of being possible, based on quality ofcorrelation and/or a model of noise in measurement and/or change inemission relative to the acquired NM data. The determined correlationmay be used to select between multiple possible positions and/or narrowdown the position of the catheter.

In an exemplary embodiment of the invention, radiation-based position iscombined with other types of positioning. For example, electricalimpedance based positioning (or other positioning methods) may beaccurate with respect to the organ, but inaccurate with respect to smallmovements of a catheter. However, if such small movements have asignificant effect on the radiation signal (e.g., emitted from a hotspot), the two signals can be combined or the radiation signal can beused to correct the impedance signal.

Even if the position sensor is precise, if organ 404 moves and/ordeforms, the position relative to the organ may be less precise. Afunctional position may be used to correct/update/replace the signal.

In some embodiments of the invention, for example, if correlationindicates multiple possible positions for the catheter, processor 120indicates a change in catheter position which should result in adifferent signal depending on the starting point of the catheter. If auser then moves the catheter, the resulting signal may then be used tofurther select between alternative approximations of the startingposition.

Signal 608 shows a measurement at location 422, near hotspot 412. Whilethere is a high peak, the secondary peaks are incorrectly located.

Signal 610 shows a central high peak (410) and two smaller side peaks(408, 412), smaller due to distance. Optionally, at this point catheter200 is moved to maximize the signal. Optionally, image reconstruction,for example as described above, is applied to better image the hot spot.

General

It is expected that during the life of a patent maturing from thisapplication many relevant nuclear medicine imaging techniques will bedeveloped and the scope of the term NM is intended to include all suchnew technologies a priori. As used herein the term “about” refers to±10%.

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean “including but not limited to”.

The term “consisting of” means “including and limited to”.

The term “consisting essentially of” means that the composition, methodor structure may include additional ingredients, steps and/or parts, butonly if the additional ingredients, steps and/or parts do not materiallyalter the basic and novel characteristics of the claimed composition,method or structure.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a compound” or “at least one compound” may include a pluralityof compounds, including mixtures thereof.

Throughout this application, various embodiments of this invention maybe presented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible subranges as well asindividual numerical values within that range. For example, descriptionof a range such as from 1 to 6 should be considered to have specificallydisclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numberswithin that range, for example, 1, 2, 3, 4, 5, and 6. This appliesregardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to includeany cited numeral (fractional or integral) within the indicated range.The phrases “ranging/ranges between” a first indicate number and asecond indicate number and “ranging/ranges from” a first indicate number“to” a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numerals therebetween.

As used herein the term “method” refers to manners, means, techniquesand procedures for accomplishing a given task including, but not limitedto, those manners, means, techniques and procedures either known to, orreadily developed from known manners, means, techniques and proceduresby practitioners of the chemical, pharmacological, biological,biochemical and medical arts.

As used herein, the term “treating” includes abrogating, substantiallyinhibiting, slowing or reversing the progression of a condition,substantially ameliorating clinical or aesthetical symptoms of acondition or substantially preventing the appearance of clinical oraesthetical symptoms of a condition.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present invention. To the extent thatsection headings are used, they should not be construed as necessarilylimiting. In addition, any priority document(s) of this applicationis/are hereby incorporated herein by reference in its/their entirety.

What is claimed is:
 1. A method of navigating to a target in a body,comprising: (a) acquiring a nuclear medicine (NM) image of a part of thebody; (b) collecting probe NM data from an intrabody probe; (c)automatically correlating said image and said probe NM data to obtaincorrelated data reflecting a match between structures in said image andstructures in the body portion of which said probe NM data is collected;and (d) automatically extracting location information of said intrabodyprobe relative to said target based on said correlated data.
 2. A methodaccording to claim 1, wherein said collecting comprises collecting whencontacting a boundary of a lumen by said probe.
 3. A method according toclaim 1, comprising: (a) using said probe NM data to generate a 3D mapof position of at least part of a boundary of said lumen and defining aboundary location and (b) using said boundary location as a constraintduring reconstruction of probe NM data of said body portion.
 4. A methodaccording to claim 3, wherein said using as a constraint comprisesassuming emissions cannot come from said lumen.
 5. A method according toclaim 1, wherein said extracting comprises using said NM data as aconstraint on probe location.
 6. The method according to claim 1,comprising reconstructing in a locality of a position of the probe whencollecting probe data.
 7. A method according to claim 1, comprisesreconstructing an image using said probe NM data.
 8. A method accordingto claim 1, comprising reconstructing a local NM image from saidlocation information and said probe NM data.
 9. The method of claim 1,comprising co-registering said location information of said intrabodyprobe to said NM image.
 10. The method of claim 1, wherein said probe isa catheter, said lumen is in the heart and one or both of said NM dataand said probe NM data comprises emissions from mIBG.
 11. A methodaccording to claim 1, wherein said correlating comprises correlatingsaid collected data with an expected set of measurements calculatedusing said NM image.
 12. A method according to claim 1, wherein saidextracting location information comprises verifying a position of saidprobe.
 13. A method according to claim 1, wherein said extractinglocation information comprises selecting between alternative positedpositions of said probe.
 14. A method according to claim 1, wherein saidextracting location information comprises determining a position of saidprobe.
 15. A method according to claim 1, wherein said extractinglocation information comprises determining a plurality of, but fewerthan 5, alternative positions of said probe.
 16. A method according toclaim 1, wherein said extracting location information comprisesdetermining a proximity to a hot spot.
 17. A method according to claim1, comprising combining said extracted information with position dataprovided by a position sensing system.
 18. A method according to claim17, wherein said combining comprises providing a functional correctionusing said NM data to a physical position indicated by said positioningdata.
 19. A method according to claim 1, wherein said collectingcomprises collecting data with a substantially omni-directional sensor,with a directional sensitivity that is within a factor of 1:2 over alldirections.
 20. A method according to claim 19, wherein collectingcomprises moving said probe to collect a non-scalar indication of NMdata.
 21. A method according to claim 1, wherein said collectingcomprises collecting data with an asymmetric sensor, with a directionalsensitivity that is within a factor more than 1:2 for at least 1% of afield of view thereof.
 22. A method according to claim 20, whereincollecting comprises moving and/or rotating said probe to collectadditional NM data for use in said correlating.
 23. A method accordingto claim 1, wherein said correlating comprises correlating based on apattern of peaks and/or amplitude of peaks in said NM data. 24.Apparatus comprising circuitry with: (a) one or more inputs forreceiving NM image data; (b) one or more inputs for receiving probe NMdata and, configured to correlate the NM data and NM image data andextracting location information of said probe therefrom.
 25. Apparatusaccording to claim 24, as part of a system comprising a catheter with aradiation sensor.